54 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



time during which the leptocephalus metamorphosis is being com- 

 pleted. By means of this method, Gemzoe ascertained that the male 

 eels remain in fresh water four and one-half to eight and one-half 

 years, and the females somewhat longer, from six and one-half to 

 eight and one-half years. Adding to these figures the year and a half 

 which was passed in the ocean in the larval stage, "it appears that a 

 female eel must be from eight to ten years old before it assumes the 

 livery of maturity and descends to the ocean to reproduce its kind." 

 The literature regarding the natural history of the eel is enormous, 

 but most of the older papers are of little scientific worth. The 

 following list comprises some of the most important of the recent 

 papers on the subject: 



1880. J AGO BY, L., Die Aalfrage (Berlin, 1880), translated in 

 Report U. S. Fish Com., 1882, 463. 

 [This paper gives an interesting and detailed account of 

 the older investigations of the subject.] 

 1888. Raffaele, Pelagic Eggs and Larvse of Fishes occurring in 

 the Gulf of Naples, 

 Mitt. Zool. Stat. Neap. B. VIII. 

 1891. Cunningham, J. T., Reproduction and Development of the 

 Conger, 

 Journ. Mar. Biol. Ass. Vol. II, No. 1, 1891. 



1895. Cunningham, J. T., The Larva of the Eel. 

 Journ. Mar. Biol. Ass. (2) III, 1895, 278. 



[This contains a summary of our knowledge of the larval 

 forms of the European species of eels.] 



1896. Grassi, G. B., 



Proc. R. Soc. LX, 1896, 260. 

 Mon. Zool. Ital. VIII, 1897, 233. 



1901. ElGENMANN, C. H., 



Bull. U. S. Fish Com., 1901. 



[This describes systematically the Leptoccphali which have 



